Thermostatic tissue platform for intravital microscopy: 'the hanging drop' model

Intravital microscopy imposes the particular problem of the combined control of the body temperature of the animal and the local temperature of the observed organ or tissues. We constructed and tested, in the rat ileum microcirculation preparation, a new organ‐support platform. The platform consisted of an organ bath filled with physiological solution, and contained a suction tube, a superfusion tube, an intestine‐support hand that was attached to a micromanipulator and a thermometer probe. To cover the intestine we used a cover glass plate with a plastic ring glued on its upper surface. After a routine procedure (anaesthesia, monitoring and surgery), the intestine segment (2–3 cm long) was gently exteriorized and placed on the ‘hand’ of the organ support. A small part of the intestine formed a small ‘island’ in the bath that was filled with physiological salt solution. The cover glass was secured in place. The physiological salt solution from the superfusion tube, which was pointed to the lower surface of the cover glass, formed a ‘hanging drop’. The objective of the microscope was then immersed into distilled water that was formed by the cover glass plastic ring. The ‘hanging drop’ technique prevented any tissue quenching, ensured undisturbed microcirculation, provided for stable temperature and humidity, and permitted a clear visual field.     

QUALITY OF WHOLE GUTTED SALMON IN VARIOUS BULK PACKAGES

Quality attributes of whole, gutted salmon (Salmo salar) were observed during chilled storage and transportation (<1C) in various bulk packages. The bulk packages used were plastic pouches with whole salmon and modified atmospheres (MA) (50% and 100% CO₂, large tubs with whole salmon in MA (60% CO₂ and air), and traditional EPS-packages with whole salmon. In all bulk packages, except traditional packages, half or less the normal amount of ice were used. The microbial growth was evidently higher in traditionally packed salmon compared with salmon stored in atmosphere with high C0₂-content. High C0₂-content in the package inhibits bacterial growth more than low C0₂-content. Salmon in MA were evaluated as equal or better sensory quality than traditionally packaged salmon after 13 days of storage. MA had, however undesirable effects on the appearance of whole salmon: faster graying of gills and loss of clearness in eyes.     

Heat-Induced Gelation of Individual Whey Proteins A Dynamic Rheological Study

Heat-induced gelation of the bovine whey proteins [serum albumin (BSA), β-lactoglobulin (β-Lg) and α-lactalbumin (α-La)] has been studied individually and in mixture at different conditions by a dynamic rheological method. Values in the shear stiffness modulus (/G*/) appeared on heating at low protein concentration for BSA (～2%) and at intermediate concentration for β-Lg (～ 5%). α-La did not form a heat-induced gel of concentrations up to 20% (w/v). The ratio of viscous to elastic properties (loss factor) at maximum possible measuring temperature was below 0.07 for the BSA gels and 0.1–0.3 for the β-Lg gels. The temperature of gelation was highly dependent on pH. In mixture one protein could not be exchange for another without changing the gelation behavior of the mixture.     

QUALITY OF FILLETED SALMON IN VARIOUS RETAIL PACKAGES

The quality attributes of salmon filleted and retail packed directly after slaughtering or after transport in various bulk packages were observed during storage at +2C. The retail packages used were overwrap, vacuum and gas packages (40% CO₂+ 60% N₂ or 60% CO₂+ 40% N₂). Microbial growth was clearly greater in overwrapped and slightly greater in vacuum packed samples than in gas packed samples. The differences were more evident when the fillets were directly retail packed without preceding bulk transport. The sensory quality of retail gas packed samples was evaluated as only slightly better than that of retail overwrapped and vacuum-packed samples after bulk transport. The sensory quality of direct, retail gas packed samples was evaluated as clearly better than that of overwrapped and vacuum packed samples. K-values determined with both HPLC and paper strip methods increased steadily during storage, although the values determined with the HPLC method were always much higher than those determined with the rapid paper strip method.